Elastomeric Conductors and Shields

ABSTRACT

Systems and methods presented herein provide for elastic conductors. The elastic conductors may be configured with a primary that includes an elastic material and a conductive material. For example, the primary may have an elastic fiber, such as spandex, with a conductive material, such as a braided metal wire, wrapped thereabout. Alternatively, the primary may be configured from an elastic material with a conductive material, such as certain nanopartiuclates, embedded therein. The elastic conductors may be used in a variety of ways to form various types of cables. For example, the elastic conductors may be configured to form coaxial cables, USB cables, twisted pairs, etc. The elastic and flexible nature of the cables may make their uses advantageous in wiring environments that are subjected to strain or other harsh conditions. Moreover, the relatively light weight of the cables may make their uses more advantageous in transportation (e.g., aircraft, automobiles, etc.).

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to and thus the benefit of an earlier filing date from U.S. Provisional Patent Application No. 61/020,623 (filed Jan. 11, 2008), the entire contents of which are incorporated by reference.

BACKGROUND

Electrical wiring is used to conduct electrical current in a variety of applications. For example, electrical wiring is used to conduct electrical energy for the purposes of power delivery. Electrical wiring is also used in data transmissions between electronics devices. Exceptionally important applications include the various power and data delivery uses in human related services, such as transportation (e.g., plane, automobile, etc.) and medical care.

For a wire to conduct electrical current, the wire is constructed of materials with conductive properties, such as the metals copper, silver, gold, and aluminum. These materials, while malleable under certain conditions, are fairly rigid. Generally, smaller diameter or gauge wires are more flexible. However, these wires are more fragile and prone to cracking and breakage. To counter such fragility, wire manufacturers configure stranded wires which are composed of bundles of smaller gauge wires to increase the gauge of the wire and thus the conductivity. Stranded wires are commonly used for electrical applications carrying small signals (e.g., computer mouse cables) and for power cables between a movable appliance and its power source (e.g., vacuum cleaners, table lamps, and powered hand tools).

At higher frequencies, current travels near the surface of common wires because of the so called “skin effect”, resulting in increased power loss in the wires. Stranded wire might seem to reduce this effect, since the total surface area of the strands is greater than the surface area of the equivalent solid wire, but a simple stranded wire actually has a degraded skin effect when compared to a solid wire because of its increased average resistivity from air gaps within the wire. Accordingly, when power loss is a concern, single-strand wires are used.

In any case, wiring can deteriorate over time due to environmental conditions and ultimately degrade wire integrity. For example, excessive flex, chafing between adjacent wires, lack of strain relief, altitude, temperature, humidity, and/or acceleration can jeopardize the integrity of the wire. When a wire breaks, open circuit conditions are created that contribute to a loss of signal integrity, component failures, or even catastrophic fires. Due to the intermittent nature of most of cable failures, these problems are often difficult to detect and even more difficult to repair.

A common solution to relieve wire strain has been to include a “service loop” where the added length of the loop enables ease of maintenance and repair with the added value of strain relief. However, it is often impractical to include service loops. For example, in aircraft, there may exist more than 100 miles of wire that already add significantly to the overall weight of the aircraft. Additional wire for service loops significantly increases that weight of the aircraft and thus the fuel costs associated with carrying the extra weight.

SUMMARY

The systems and methods described herein provide for flexible and elastic conductors that may be designed and implemented in a variety of manners. For example, elastic conductors may be implemented using nano particulate materials (e.g., carbon nanotubes) configured with elastic fibers (e.g., spandex). Alternatively, braided metal wire may be configured about an elastomeric fiber to make the braided metal wire returned to an original shape when a stress is released. These conductors may be implemented to form coaxial cables, data cables, power cables, shielding, or the like. The advantages of elastic conductors are varied and many. For example, the elastic conductors described herein are generally resistant to breakage when placed under strain due to their flexibility and elastic nature. Moreover, the elastic fibers that may be used to form the elastic cables may be more resistant to harsher environmental conditions such as heat, moisture, and chemical exposure. Furthermore, the elastic cables are generally much lighter than their traditional metal counterparts. These attributes may be particularly useful when weight is an important consideration in wiring, such as in aircraft and space vehicles.

In one embodiment, an elastic conductive cable includes a primary configured from and including an elastic material and a conductive material configured with the primary. The conductive material may include braided metal. The braided metal may be wrapped about the primary having a first level of elasticity.

The elastic conductive cable may also include an insulator surrounding the primary and the conductive material. For example, the insulator may include spandex, polyolefin, a thermoplastic vulcanizate, or a combination thereof The elastic conductive cable may also include elastic shielding surrounding the insulator. For example, the elastic shielding may be a braided wire, a nanoparticulate material, or a combination thereof.

The elastic material may include spandex, polyolefin, a thermoplastic vulcanizate, polystyrene, versaflex, spandex, XLA, Santoprene, or a combination thereof The conductive material may include a nano particulate (e.g., carbon nanotubes). The cable may be used as a USB cable, a data cable, or a coaxial cable.

In another embodiment, a circuit includes an electronic component and an elastic electrical conductor that includes an elastic matrix material (e.g., spandex, polyolefin, a thermoplastic vulcanizate, polystyrene, or a combination thereof) and a conductive nano particulate material (e.g., carbon nanotubes) configured with the matrix material. The circuit also includes a connector affixed to an end of the elastic electrical conductor and coupled to the electronic component. The electronic component may be a data device configured with an aircraft, a vehicle, an article of clothing, or a space vehicle.

In another embodiment, an elastic coaxial cable includes a first conductor configured with an elastic matrix material and a conductive nano particulate material embedded with the elastic matrix material, an elastic insulator surrounding the matrix material, and a shielding configured about the elastic insulator. The shielding may be braided wire or an elastomeric conductor that includes carbon nanotubes.

BRIEF DESCRIPTION OF THE DRAWINGS

The same reference number represents the same element or same type of element on all drawings.

FIG. 1 is a diagram of a two elastic materials configured with one another to form an elastic electrical conductor, in one exemplary embodiment of the invention.

FIG. 2 is a block diagram of a flexible printed circuit board employing elastic electrical conductors, in one exemplary embodiment of the invention.

FIG. 3 is a perspective view of an elastic electrical conductor, in one exemplary embodiment of the invention.

FIG. 4 is a perspective cutaway view of an elastic electrical conductor configured with a braided metal primary, in one exemplary embodiment of the invention.

FIG. 5 illustrates a process for forming an elastic electrical conductor, in one exemplary embodiment of the invention.

FIG. 6 is a perspective view of another elastic electrical conductor, in one exemplary embodiment of the invention.

FIG. 7 is a diagram of an elastic coaxial cable, in one exemplary embodiment of the invention.

FIG. 8 is a flowchart of a process for forming an elastic electrical conductor, in one exemplary embodiment of the invention.

FIG. 9 is a flowchart of another process for forming an elastic electrical conductor, in one exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that it is not intended to limit the invention to the particular form disclosed, but rather, the invention is to cover all modifications, equivalents, and alternatives falling within the scope and spirit of the invention as recited in the claims.

FIG. 1 is a diagram of elastic materials 11 and 12 configured with one another to form an elastic electrical conductor 10, in one exemplary embodiment of the invention. The material 12 acts as a matrix material that serves as a sort of substrate for the elastic conductive material 11. For example, the material 12 may have insulative properties that allow for the conductive material 11 to controllably conduct electric current. In this regard, the material 12 may be configured with the material 11 being contained therein to conduct the electric current along a path. Alternatively, the matrix material may be configured in a relatively flat manner with the conductive material 11 being configured as circuit traces thereon to serve as a flexible printed circuit board.

In any case, the materials 11 and 12 are flexible and elastic and may provide for electric conductivity with reduced faults. For example, the flexible and elastic nature of the conductor may reduce the number of breaks or faults when compared to traditional cables and wires employing metal conductors, such as copper. Cables and wires are often subject to strains and/or environments that reduce conductivity and/or cause intermittent conduction in traditional cables and wires. In some cases, traditional wires even fail completely. The materials 11 and 12 may overcome such inadequacies by providing electrical conductors that are more resistant to strain and/or harsh operating environments.

FIG. 2 is a block diagram of a flexible printed circuit board 20 employing an elastic electrical conductor 22, in one exemplary embodiment of the invention. In this embodiment, the flexible printed circuit board may be configured of the matrix material 12 having the conductive material 11 “printed” as traces on the matrix material 12 to form the printed circuit board 20. In this regard, electrical components 21 and 23 may be configured on the printed circuit board 20 and coupled to one another via the conductive material 11 and couplings 24 (e.g., connectors, solder, glue, etc.). As mentioned, the flexible and elastic nature of the materials 11 and 12 may make the printed circuit board 20 more resistant to strain and/or relatively harsh operating environments. For example, the printed circuit board 20 may be configured with clothing. When worn, the printed circuit board 20 may be subjected to a variety of stresses that would break a traditional, more rigid printed circuit board. The printed circuit board 20, on the other hand, may bend and flex almost as easily as the clothing. Moreover, because the printed circuit board 20 is so elastic and flexible, the printed circuit board 20 may be worn comfortably by the user. Such a feature may be of significance to the user when a particular piece of clothing is configured with a substantial number of electronics. For example, soldiers in battle are often being required to carry more electronics has part of the “soldier as a system” initiative by the Department of Defense. These flexible printed circuit boards (e.g., the printed circuit board 20) may assist the soldier in carrying more electronics more comfortably.

Moreover, the materials 11 and 12 are generally configured from lighter materials that make an overall electronic system lighter for the soldier. For example, the conductive material 11 may be configured of carbon nanotubes and/or other nano particulates that are typically lighter than conductive metals, such as copper. Examples of carbon nanotubes include single walled carbon nanotubes that are generally shaped in a tube having a diameter of about 1 nanometer and a tube length that is much longer. These nanotubes exhibit similar electric properties of conductivity and electromagnetic shielding that are found in their metal counterparts. The material 12 may be configured from a similarly lightweight material, such as spandex. Combined, the materials 11 and 12 provide for an electronics system that is lighter than traditional worn electronics.

FIG. 3 is a perspective cutaway view of an elastic electrical conductor 30, in one exemplary embodiment of the invention. In this embodiment, the elastic electrical conductor 30 is configured from two materials 31 and 32. The material 32 surrounds the material 31 to form the elastic electrical conductor 30. Both materials 31 and 32 provide a certain measure of elasticity to make the electrical conductor 30 elastic and resistant to strains and breaks. In one embodiment, the material 31 is both elastic and conductive. The material 32 in such an embodiment provides the electrical conductor 30 with elastic insulative properties.

To provide such an elastic conductor, the material 31 may be configured from a nano particulate material, such as a carbon nanotube, embedded with an elastic synthetic fiber. For example, elastomeric fibers such as Spandex may be fabricated in a variety of manners including melt extrusion, reaction spinning, solution dry spinning, and solution wet spinning. These methods include the initial step of reacting monomers to produce a prepolymer. The carbon nanotubes may be formed and embedded with the Spandex when the prepolymer is formed. Embedding a sufficient amount of the nanotubes with the prepolymer may ensure that the nanotubes remain in contact with one another once the prepolymer is formed and drawn out to produce fibers. Thus, the conductivity of the elastomeric wire is maintained.

An example of an elastic material that may be used for material 32 and/or material 31 includes spandex, although other materials may be used (e.g., polyolefin, thermoplastic vulcanizates, polystyrene, combinations thereof, etc.). The invention, however, is not intended to be limited to a particular elastic material.

In another embodiment, the electrical conductor 30 is configured with an elastic material 31 lacking nano particulates. In such an embodiment, the material 31 provides an elastic matrix to which a conductive material may be applied. For example, the material 31 may provide a base of elasticity to the electrical conductor 30. Thereafter, a conductive material 32, such as a braided metal, may be applied to the material 31 (e.g., wrapped about).

A braided metal may be configured with relatively lightweight and very thin metal that allows for the conductor to be stretched. In one embodiment, the braided metal is configured with a braiding machine, such as that produced by Steeger USA, to braid fine metal wire over the material 31. The braided metal may be stretched to some degree. Since braided metal generally does not return to its original shape once the stress is removed, the elasticity of the material 31 returns the electrical conductor 30 and thus the braided metal 32 to a rest condition of the material 31 when the stress to the electrical conductor 30 is no longer applied (e.g., the electrical conductor 30 is no longer being stretched). To make such an elastic conductor 30 safe, the conductor may then be configured with an insulative material about the braided metal, as shown and described below.

FIG. 4 is a perspective view of an elastic electrical conductor 40 with a braided metal primary 43, in one exemplary embodiment of the invention. As discussed in the description of FIG. 3, the braided metal primary 43 is configured about elastomeric wire 44 so as to make the electrical conductor 40 elastic. The braided metal primary 43 may have a similar level of “stretch” as the material forming the elastomeric wire 44. However, conductive metals like that of the braided metal primary 43 generally do not retain their original shapes when strained or stretched. In other words, the braided metal primary 43 may stretch in a lengthwise manner 45 when pulled on the ends of the elastic electrical conductor 40 and remain in the stretched position after the strain is released. The elastomeric wire 44, thus, provides the braided metal primary 43 with the elasticity to return the braided metal wire 43 to the original shape, or rest position, once the strain is removed.

The braided metal primary 43 may be configured in a variety of ways from a variety of materials. For example, the braided metal primary 43 may be configured in a manner resembling a coaxial shielding and configured from similar materials, such as aluminum, copper, silver, gold, or the like. The elastomeric wire 44 may be configured by extruding a material such as Versaflex, Spandex, XLA (by Dow Corporation), Santoprene, or the like, into a fiber, although other processes for making an elastic fiber may be used. Afterwards, the braided metal primary 43 may be configured about the elastomeric wire 44. With the primary portion of the elastic electrical conductor 40 configured (i.e., the braided metal primary 43 and the elastomeric wire 44), the primary may be wrapped with an insulator 42 and a cable protector 41. Examples of materials that may be used as an insulator 42 and a cable protector 41 include Kapton and polyetrafluoroethylene (PFTE). For example, Kapton may be configured with Teflon (i.e., PFTE) as a “TKT” wire wrap or tape that wraps about the primary of the elastic electrical conductor 40 to insulate the elastic electrical conductor 40. Thereafter, a Teflon tape may be wrapped about the TKT to protect the cable. The invention, however, is not intended to be limited to a particular material for insulating/protecting the elastic electrical conductor 40. Rather, other suitable materials may be used. For example, the elastic electrical conductor 40 may be surrounded by an elastomeric material such as those described above. In one embodiment, the primary may be encased within an insulating material, such as spandex, by extruding the primary with the insulating material.

FIG. 5 illustrates a process for forming an elastic electrical conductor 55, in one exemplary embodiment of the invention. In this embodiment, the elastic electrical conductor 55 is configured with a plurality of elastic conductive wires 52 and surrounded by an elastic insulator 53. The elastic conductive wires 52 may be configured from a nano particulate material provides a certain level of conductivity while remaining fairly elastic. For example, carbon nanotubes are relatively conductive and may be useful in various types of cabling, such as data and communication cables. When the carbon nanotubes are embedded with the elastomeric material 53, the entire electrical conductor 55, in essence, becomes elastic. Afterwards, the elastic electrical conductor 55 may be wrapped with a Teflon tape or other suitable material 51 to protect and further insulate the conductive material 52 within the conductor 55. Once wrapped, the electrical conductor 55 is heated via the heater 50 to sinter the protective material 51 onto the electrical conductor 55.

FIG. 6 is a perspective view of an elastic electrical conductor 60, in one exemplary embodiment of the invention. In this embodiment, the electrical conductor 60 is configured with a plurality of elastic conductive wires 61 wrapped with an insulating material 62 (e.g., TKT) and further wrapped with a PFTE wrapper 63. The materials 62 and 63 may be sintered to protect and insulate the electrical conductor 60, as discussed above.

FIG. 7 is a diagram of an elastic coaxial cable, in one exemplary embodiment of the invention. In this embodiment, the coaxial cable 70 is configured with a conductive primary 71 as is typical of many coaxial cables. Differing from traditional coaxial cables, however, is the elasticity of the material used in the primary 71. For example, the primary 71 may be configured from a plurality of conductive fibers having a certain level of elasticity that allow for the overall coaxial cable 70 to stretch. In one embodiment, the primary 71 is configured from a nano particulate material, such as carbon nanotubes, embedded with synthetic elastic fiber. The primary 71 may be surrounded by a dielectric material 72 having a similar level of elasticity. For example, a material such as spandex may be used to insulate the primary 71, ensuring that the overall inner portion of the coaxial cable 70 a certain level elasticity.

Once the primary 71 is formed, the primary may be wrapped in an insulating material 73. For example, the primary 71 may be wrapped in a Teflon tape and sintered to ensure that the conductive portions of primary 71 remain insulated. Thereafter, the coaxial cable 70 may be configured with a braided wire shielding 74. The braided wire shielding 74 may have a certain level of stretch as with the braided wire 40 of FIG. 4. Thus, when the coaxial cable 70 is stretched over some distance, the elasticity of the primary 71 may return the coaxial cable 70 to its original shape when the stress is removed. However, the invention is not intended to be limited to simply braided wire, as conductive nanotubes or other suitable materials may be configured about the insulation 73 of the coaxial cable 70 to provide electromagnetic shielding. With the shielding 74 in place, the coaxial cable may be configured with another insulating material 75 to protect the inner components of the coaxial cable 70. Such an insulating material 75 may include a variety of materials including TKT or an elastomeric material to ensure that the coaxial cable 70 remains fairly elastic and flexible.

FIG. 8 is a flowchart of a process 100 for forming an elastic electrical conductor, in one exemplary embodiment of the invention. In this embodiment, a polymer used in fabricating elastic fibers is formulated, in the process element 101. For example, Spandex fibers may be produced by melt extrusion, reaction spinning, solution dry spinning, or solution wet spinning to produce a polymer. Once the prepolymer is formed, a conductive nano particulate material such as carbon nanotubes may be embedded with the polymer, in the process element 102. Thereafter, the polymer may elasticized via traditional processing to make the conductive nano particulate material seemingly elastic, in the process element 103. The combined material may then be extruded to form a conductive primary, in the process element 104. However, other manners for making the synthetic fibers may be used (e.g., reaction spinning, solution dry spinning, and solution wet spinning). With the conductive primary configured, an elastic insulator may be applied to the primary to insulate the conductive wire, in the process element 105. For example, the primary may be wrapped with a Teflon or a TKT material and sintered to the insulator, although other materials may be used. Alternatively or additionally, the braided wire may be configured from a nano particulate material, such as carbon nanotubes, as opposed to metal wire. In one embodiment, the shielding may even be formed in a manner that is similar to the conductors themselves. For example, the shielding may be extruded along with the elastic conductor in a process that has nanoparticulate material embedded in layers of elastic non conductive material (e.g., spandex). That is, the nanoparticulate material may be embedded within the elastic material in such way that layers of conductive material are formed as an elastic wire such that one or more layers may are used for electrical propagation (e.g., data) and another one or more layers are used for shielding.

Those skilled in the art should readily recognize that the invention is not intended to be limited to a conductive primary formed with conductive nano particulate material and elastomeric fiber. Rather, other materials may be used to form the conductive portion of the primary. For example, FIG. 9 illustrates a flowchart of a process 120 for forming an elastic coaxial cable, in one exemplary embodiment of the invention. In this embodiment, a polymer (e.g., spandex, polyolefin, thermoplastic vulcanizates, etc.) may be formulated in the process element 121 and then elasticized in the process element 122. Thereafter, synthetic fibers are formed to assist in forming a primary, in the process element 124. For example, the elastic fiber may be surrounded by a braided metal wire, in the process element 124, to serve as a conductor. The braided metal wire may be configured in such a way as to endure certain amount of stretch. However, braided metal wire generally does not return to its shape once extended. Rather, the elastic fiber to which the braided metal is configured returns the elastic conductor to a rest position once a stress is removed. Thereafter, the conductive cable may be configured with an insulating material, in the process element 125.

The invention is not intended to be limited to the processes for forming an elastic electrical conductor described in FIGS. and 8 and 9. For example, other steps may be performed and/or the illustrated steps may be rearranged in other manners that fall within the scope and spirit of the invention. For example, an elastic coaxial cable may be fabricated by embedding nano particulate material within an elastomeric fiber. Thereafter, the coaxial cable may be insulated with an elastic material and surrounded by a braided to wire and further insulated to form the coaxial cable. Alternatively, the elastic coaxial cable may be fabricated by surrounding elastomeric fiber with braided metal wire to form a primary. Thereafter, the primary may be surrounded by an insulator and another conductive material (e.g., braided metal wire or a nano particulate material embedded with an elastomeric material).

The elastic electrical conductors may have a variety of advantageous uses. For example, flexible elastic wires can improve, among other things, wire and cable reliability, body worn comfort, and weight reduction. Flexible elastic wires may make the wires less susceptible to breakage and/or faults associated with intermittent conductivity. Moreover, the relatively light weight of the elastomeric fibers may reduce energy associated with transporting such cables. For example, lighter cables in the airline industry directly reduce the overall weight of an aircraft thereby reducing the expense of transporting heavier cables. The lighter weight and flexibility of the cables also provides a more effective means for wearable electronics. For example, as more electronics are integrated with clothing (e.g., a soldier's uniform), lighter weights are required so that the person may be capable of relatively unrestricted movement. The lightweight of elastomeric cables described herein make that possible. However, the invention is not intended to be limited to a particular use.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character. For example, certain embodiments described hereinabove may be combinable with other described embodiments and/or arranged in other ways (e.g., process elements may be performed in other sequences). Accordingly, it should be understood that only the preferred embodiment and variants thereof have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. 

1. An elastic conductive cable, including: a primary configured from and including an elastic material; and a conductive material configured with the primary.
 2. The elastic conductive cable of claim 1, wherein the conductive material includes braided metal.
 3. The elastic conductive cable of claim 2, wherein the braided metal is wrapped about the primary and has a first level of elasticity.
 4. The elastic conductive cable of claim 1, further including an insulator surrounding the primary and the conductive material.
 5. The elastic conductive cable of claim 4, wherein the insulator includes spandex, polyolefin, a thermoplastic vulcanizate, or a combination thereof.
 6. The elastic conductive cable of claim 4, further including elastic shielding surrounding the insulator.
 7. The elastic conductive cable of claim 6, wherein the elastic shielding is a braided wire, a nanoparticularte material, or a combination thereof.
 9. The elastic conductive cable of claim 1, wherein the elastic material includes spandex, polyolefin, a thermoplastic vulcanizate, polystyrene, versaflex, spandex, XLA, Santoprene, or a combination thereof.
 10. The elastic conductive cable of claim 1, wherein the conductive material includes a nano particulate.
 11. The elastic conductive cable of claim 1, wherein the conductive material includes carbon nanotubes.
 12. The elastic conductive cable of claim 1, wherein the cable is a USB cable, a data cable, or a coaxial cable.
 13. A circuit, including: an electronic component; an elastic electrical conductor that includes an elastic matrix material and a conductive nano particulate material configured with the matrix material; and a connector affixed to an end of the elastic electrical conductor and coupled to the electronic component.
 14. The circuit of claim 13, wherein the nano particulate material includes carbon nanotubes.
 15. The circuit of claim 13, wherein the matrix material includes spandex, polyolefin, a thermoplastic vulcanizate, polystyrene, or a combination thereof.
 16. The circuit of claim 13, wherein the electronic component is a data device of an aircraft, a vehicle, an article of clothing, or a space vehicle.
 17. The circuit of claim 13, further including an elastic shielding.
 18. The circuit of claim 17, wherein the elastic shielding includes a braided wire or an elastomeric conductor that includes carbon nanotubes.
 19. The circuit of claim 13, wherein the matrix material and the conductive nano particulate material are configured with a flexible printed circuit board.
 20. The circuit of claim 13, wherein the matrix material and the conductive nano particulate material are configured as a wire.
 21. The circuit of claim 20, wherein the wire is configured with a USB cable, a coaxial cable, a firewire cable, or a twisted pair cable.
 22. An elastic coaxial cable, including: a first conductor configured with an elastic matrix material and a conductive nano particulate material embedded with the elastic matrix material; an elastic insulator surrounding the matrix material; and a shielding configured about the elastic insulator.
 23. The elastic coaxial cable of claim 22, wherein the shielding is braided wire or an elastomeric conductor that includes carbon nanotubes. 